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The Storage Environment

The storage environment into which a record is placed can, have a dramatic effect on the long-term usefulness of that record and the information it contains. Key environmental factors are: temperature, relative humidity, pollutants light

Air may contain excessive moisture, pollutants, microorganisms and other particles that accelerate the deterioration of paper. Dirt and dust particles can scratch film and tape emulsions and carry pollutants that may promote paper degradation.

Because records do not possess the human ability to recuperate, we look for preventive means to minimize damage from the environment. Controlling temperature, relative humidity, and light and keeping the environment clean can have a dramatic effect on the longevity of records.

Temperature and Relative Humidity

Records exposed to high levels of heat, humidity, light, and dirt degrade more quickly than records stored under conditions that are cool, dry, dark, and, clean. Research has shown that cooler temperatures can dramatically reduce the rate of degradation of all records.

A target temperature and relative humidity for storing records composed of a variety of materials is 68º F. + 2º F and 40% + 5% relative humidity (RH). The true goal is to provide a stable environment, keeping, as close as possible to the levels suggested with minimal fluctuations. Some heating and cooling systems come with programmable thermostats that provide varying temperature schedules. While these may save fuel by shutting down the system, they will also increase the period of time that records are not stored under desired conditions. Keep conditions as consistent as possible. Maintain the building housing records at the same temperature and relative humidity 24 hours a days, seven days a week. Do not store permanent records in barns, equipment sheds or any other buildings that do not have the capacity for heating and cooling as needed.


Excessive heat, poor air circulation, and relative humidity above 65% can provide a suitable climate for mold growth. High humidity is especially problematic in basements, where ground water and cooler temperatures encourage water vapor to collect. The appearance of mold indicates a serious condition -- take immediate action.

When mold occurs, reduce the temperature and relative humidity. Do not move records or try to remove mold from records without first consulting with preservation personnel.

Determining the mold species, is an important first step in addressing the mold outbreak.

Some molds can present very serious health concerns. Even dormant (dry or powdery) mold spores can be readily redistributed within a storage space, becoming active (velvety) when environmental conditions are favorable for, and growth. Lowering temperature and relative humidity levels and increasing air circulation are required discourage future mold growth. 


Light, whether natural or artificial, can weaken some materials causing them to fade or darken. Damage from light is irreversible and the effects of exposure accumulate over time. A record exposed to a dim light for a long time, will ultimately, show the same effects as a record, exposed to a bright light for a short time. Reduce exposure to the greatest degree possible. Cover windows with shades or drapes that block light entirely. Blocking light in this manner will also help keep a more stable temperature by reducing solar heat gain. Turn off interior lights when not in use. Storing materials in folders and boxes is an excellent way to protect records from light.

Photocopiers can be a powerful source of light. Avoid repeatedly, copying the same record. Create " use" copies for heavily requested records. If you provide users with surrogate copies you can reduce wear and tear on the originals.

Dust and Pollutants

State-of-the-art repositories use chemical filtration to remove pollutants from the air.

Even without an expensive filtration system there are a number of ways to limit the effects of pollutants. One important way is to house records within folders and boxes that meet the

American National 'Standards Institute (ANSI) standard for permanence, Z39.48-1992. The alkaline reserve in these materials will serve as a buffer between the contents and a potentially harsh environment. Boxes and folders meeting the ANSI, standard will create a stable microenvironment for permanent records.

Other steps you can take include:

  • Maintaining an overall environment that is as dust-free as possible.
  • Changing furnace and air conditioner filters on a regular schedule, e.g., quarterly.
  • Using vacuum cleaners equipped with hi-efficiency particulate air (HEPA) filters if possible, so as not to redistribute dust.
  • Avoiding the introduction of materials that create internal pollutants such as wooden cabinets and shelves, cleaning compounds, and carpeting.
  • Avoiding the storage of records near copying machines, which produce ozone and dust from toner.


A pest infestation not only creates anxiety among staff, it can cause, significant damage to records. Environmental problems such as high relative humidity, gaps in the building envelope, or poor housekeeping indicate an insect problem. Remove trash daily from inside the building and do not allow collected trash to accumulate in areas directly outside the building. A clean and environmentally controlled building will discourage pests from making their home in storage areas.

Unless there is a specific problem to be addressed avoid regularly scheduled chemical treatments. There is no all-purpose chemical for eliminating every pest problem. Moreover, chemicals that emit strong odors may create long-term problems for staff, records, and record users. Glue traps contain no chemicals and are useful for determining the existence and type of pest present. Such monitoring devises can be furnished by your local pest control technician or purchased in hardware stores.

Limiting food and beverages to designated areas, monitoring the environment, using identification and least toxic eradication methods first, and working with your pest control technician are all part of a preventive approach known as integrated pest management, or IPM.

A pest infestation inside records boxes indicates a serious condition. Consult a conservator immediately.

By providing an optimal environment for the records entrusted to your care, you help to ensure the preservation of your community's unique heritage for present and future generations of Iowans.

The following publications are available for onsite use or temporary loan through the Iowa Historical Records Advisory Board's Resource Library.

Resources and Publications

The following publications are available for on-site use or temporary loan through the Iowa Historical Records Advisory Board's Resource Library.

Collections Care. What to Do When You Can 't Afford to Do Anything. American Association for State and Local History, Technical Leaflet 198. 1997.

How to Control Environmental Conditions in Historical Agencies and Museums. American Association for State and Local History, Technical Report 3. 1985.

Storage Solutions for Oversized Paper Artifacts. American Association for State and Local History, Technical Leaflet 188. 1994.

Environmental Controls for Local Government Records. American Association for State and Local History, NICLOG Technical Leaflet 111. 1989.

For Assistance or Additional Information, Contact:

Iowa Historical Records Advisory Board (IHRAB)
Jeffrey Dawson, Archives Supervisor 
State Historical Society of Iowa
600 East Locust, Des Moines, 1A 50319

This pamphlet is based on one originally prepared by the Georgia Department of Archives and History. This adaptation was prepared with funds provided by the National Historical Publications and Records Commission.

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